cc/ipc: Null check deserialized filters.

Reject SkImage filters if they fail to deserialize, instead of creating
a FilterOperation with a null filter.

Also fix incorrect enum type on ImageFilterPaintFilter.

R=enne@chromium.org, tsepez@chromium.org

Bug: 
Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.android:android_optional_gpu_tests_rel
Change-Id: I3cd93fd671e679ac6e8881d75abc47a50d9b5d59
Reviewed-on: https://chromium-review.googlesource.com/791937
Commit-Queue: Khushal <khushalsagar@chromium.org>
Reviewed-by: enne <enne@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#519587}

cc/ipc/cc_param_traits.cc

@@ -293,13 +293,18 @@ bool ParamTraits<sk_sp<SkImageFilter>>::Read(const base::Pickle* m,
   int length = 0;
   if (!iter->ReadData(&data, &length))
     return false;
-  if (length > 0) {
-    SkFlattenable* flattenable = skia::ValidatingDeserializeFlattenable(
-        data, length, SkImageFilter::GetFlattenableType());
-    *r = sk_sp<SkImageFilter>(static_cast<SkImageFilter*>(flattenable));
-  } else {
+
+  if (length <= 0) {
     r->reset();
+    return true;
   }
+
+  SkFlattenable* flattenable = skia::ValidatingDeserializeFlattenable(
+      data, length, SkImageFilter::GetFlattenableType());
+  if (!flattenable)
+    return false;
+
+  *r = sk_sp<SkImageFilter>(static_cast<SkImageFilter*>(flattenable));
   return true;
 }
 

cc/paint/paint_filter.h

@@ -239,7 +239,7 @@ class CC_PAINT_EXPORT AlphaThresholdPaintFilter final : public PaintFilter {
 
 class CC_PAINT_EXPORT ImageFilterPaintFilter final : public PaintFilter {
  public:
-  static constexpr Type kType = Type::kImage;
+  static constexpr Type kType = Type::kSkImageFilter;
   const SkImageFilter* sk_filter() const { return sk_filter_.get(); }
 
  private:

skia/public/interfaces/image_filter_struct_traits.h

@@ -47,6 +47,11 @@ struct StructTraits<skia::mojom::ImageFilterDataView, sk_sp<SkImageFilter>> {
     SkFlattenable* flattenable = skia::ValidatingDeserializeFlattenable(
         buffer.data->bytes(), buffer.data->size(),
         SkImageFilter::GetFlattenableType());
+    if (!flattenable) {
+      *out = nullptr;
+      return false;
+    }
+
     *out = sk_sp<SkImageFilter>(static_cast<SkImageFilter*>(flattenable));
     return true;
   }